import { addClass, removeClass } from './shared.js';

function Transition() {

}

Transition.prototype.beforeEnter = function (el) {
	addClass(el, 'collapse-transition');
	if (!el.dataset) el.dataset = {};

	el.dataset.oldPaddingTop = el.style.paddingTop;
	el.dataset.oldPaddingBottom = el.style.paddingBottom;

	el.style.height = '0';
	el.style.paddingTop = 0;
	el.style.paddingBottom = 0;
}

Transition.prototype.enter = function (el) {
	setTimeout(function () {
		// el.style.overflow = 'hidden';
		el.dataset.oldOverflow = el.style.overflow;
		if (el.scrollHeight !== 0) {
			el.style.height = el.scrollHeight + 'px';
			el.style.paddingTop = el.dataset.oldPaddingTop;
			el.style.paddingBottom = el.dataset.oldPaddingBottom;
		} else {
			el.style.height = '';
			el.style.paddingTop = el.dataset.oldPaddingTop;
			el.style.paddingBottom = el.dataset.oldPaddingBottom;
		}
	}, 0)
}

Transition.prototype.afterEnter = function (el) {
	removeClass(el, 'collapse-transition');
	el.style.height = '';
	el.style.overflow = el.dataset.oldOverflow;
}

Transition.prototype.beforeLeave = function (el) {
	addClass(el, 'collapse-transition');

	if (!el.dataset) el.dataset = {};
	el.dataset.oldPaddingTop = el.style.paddingTop;
	el.dataset.oldPaddingBottom = el.style.paddingBottom;
	el.dataset.oldOverflow = el.style.overflow;

	el.style.height = el.scrollHeight + 'px';
	el.style.overflow = 'hidden';
}

Transition.prototype.leave = function (el) {
	addClass(el, 'collapse-transition');
	if (el.scrollHeight !== 0) {
		// for safari: add class after set height, or it will jump to zero height suddenly, weired
		el.style.height = 0;
		el.style.paddingTop = 0;
		el.style.paddingBottom = 0;
	}
}

Transition.prototype.afterLeave = function (el) {
	removeClass(el, 'collapse-transition');
	el.style.height = '';
	el.style.overflow = el.dataset.oldOverflow;
	el.style.paddingTop = el.dataset.oldPaddingTop;
	el.style.paddingBottom = el.dataset.oldPaddingBottom;
}


// 返回一个函数式组件
export default {
	name: 'ElCollapseTransition',
	functional: true,
	render(h, { children }) {
		const data = {
			on: new Transition()
		};
		return h('transition', data, children);
	}
};
